Department of Agriculture and Food research scientist Chengdao Li homed in on the acid tolerant gene in the recently released barley variety LitmusTM using a genetic method akin to a game of battleships.
“Basically we played a sophisticated version of battleships with the barley genome until we were able to mark the general coordinates of the acid-tolerance gene,” Dr Li said.
“We were then able to ensure that the gene was present in the breeding population that eventually produced LitmusTM.”
With more than 20,000 genes in the barley genome, being able to narrow in on a specific gene meant the new variety was delivered to growers more quickly.
Without the gene’s coordinates, Dr Li would have been forced to grow thousands of barley plants in acid soil for several years to select a breeding line carrying the valuable acid tolerant gene.
“The marker method speeds the plant breeding process because it allows us to test batches of seed or individual leaves from very young plants to determine if they have a specific gene, rather than having to grow seed to fully grown plants and measure their response to a particular field constraint like acid soil,” he said.
Dr Li combined the marker method with another genetic technique known as ‘doubled haploid’ technology to package up a set of genetically similar and stable barley plants from which plant breeding collaborators InterGrain and Syngenta then developed LitmusTM.
Department research officer Sue Broughton is a national expert in doubled haploid technology having spent the past 20 years refining the method for wheat and barley breeding and research programs across Australia.
“LitmusTM began its life in our doubled haploid laboratory in 2004 when we crossed a barley breeding line known to contain the acid-tolerant gene with an early maturity breeding line with good agronomic and malting characteristics,” Ms Broughton said.
Progeny from the cross were then tested for acid tolerance using Dr Li’s marker coordinates method.
“Of the thirteen plants tested only six contained the acid-tolerance gene,” Ms Broughton said.
Using the doubled haploid method, Ms Broughton collected microspores (immature pollen cells) from the six acid-tolerant plants and generated 140 barley plants directly from the microspores, which were then grown out in seedling trays.
“It’s a fascinating technique,” Ms Broughton said. “Creating plants directly from microspores rather than seed means we can fix the genetics of a breeding line to ensure it breeds true for a particular characteristic much earlier than if we had to grow out and collect seed over several generations in the field.”
Using Dr Li’s molecular marker method, individual leaves from each of the 140 doubled haploid plants were tested for the acid-tolerant gene. “Those plants containing the gene were then handed over to InterGrain to evaluate their performance in acid soils across Australia,” Ms Broughton said.
The best line was released as LitmusTM.
Dr Li is now focused on locating other acid-tolerant genes within the barley genome and is also developing a more accurate marker method for his crop genetics research.
“The new method will be 100 per cent accurate for specific genes,” Dr Li said. “It will remove some of the inaccuracies of the current method and make new variety development even faster.”
LitmusTM is the first acid soil tolerant barley variety to be released in Western Australia with potential to meet export malting quality standards. The new variety yields up to 20 per cent more than currently available barley varieties on acid soils.
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